Annchienta is a 2D isometric game engine for RPG
games, but it can be used for other games as well.
Games available for it are mostly set in a
fantasy world, combining an epic and tragic quest
with fun and challenging gameplay.

Asymptopia BlackJack is a full-featured casino-style blackjack game written in Python using PyGame for graphics. You play with up to 6 robots against the dealer. You can specify which player is you. It is dynamic, addictive, and you don't lose real money!

Atanks is a multi-platform Scorched Earth clone
similar to the Worms series of games. Annihilate the other tanks to earn money, then spend it on bigger and better
shields and weapons to wipe out the opposition. It
features a wide array of weapons, AI players, destructible
landscape, weather, parachutes, teleports and a
wide range of other features.

Atoms for PalmOS is a two player game. Each turn a player can place an atom inside a square. If the square is full then it will explode by placing one atom in every neighbour square, and any enemy atoms there are taken over by you.

BBalc is an open framework for the BloodBowl game. The purpose of this library is to provide chess-computer like functions like analyzing the game or generating BloodBowl actions. It provides a versatile interface to access and modify game data. The modular design allows users to extend existing analyse modules to their needs, build new modules from scratch, or even build complete applications based on the BBalc framework.